# IGT vtkMRMLIGTLConnectorNode best way to know how long to wait for connection and node access?

**URL:** <https://discourse.slicer.org/t/igt-vtkmrmligtlconnectornode-best-way-to-know-how-long-to-wait-for-connection-and-node-access/5417>\
**Category:** Development\
**Tags:** openigtlink\
**Created:** [January 18, 2019, 11:31pm UTC](https://discourse.slicer.org/t/igt-vtkmrmligtlconnectornode-best-way-to-know-how-long-to-wait-for-connection-and-node-access/5417 "2019-01-18T23:31:30Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![NormandRobert](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/normandrobert/32/4818_2.png) [@NormandRobert](https://discourse.slicer.org/u/NormandRobert)\
**Post date:** [January 18, 2019, 11:31pm UTC](https://discourse.slicer.org/t/igt-vtkmrmligtlconnectornode-best-way-to-know-how-long-to-wait-for-connection-and-node-access/5417/1 "2019-01-18T23:31:30Z")

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Operating system: Ubuntu16.04.4  
Slicer version: 4.8.1

navigationHostName=‘fusion’  
navigationPortNumber=‘18944’  
connectorNodeNav = slicer.vtkMRMLIGTLConnectorNode()  
connectorNodeNav.SetTypeClient(navigationHostName,int(navigationPortNumber))  
slicer.mrmlScene.AddNode(connectorNodeNav)  
connectorNodeNav.Start()

print “NumberOfIncomingMRMLNodes=”, connectorNodeNav.GetNumberOfIncomingMRMLNodes()

How long to wait before I get correct values?  
Line above yields 0 in interpreter if I paste code above in one go and 3 as expected if I wait a bit before pasting the last line. This code in a module always yields zero. Advice? Block on something?

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [January 19, 2019, 3:17am UTC](https://discourse.slicer.org/t/igt-vtkmrmligtlconnectornode-best-way-to-know-how-long-to-wait-for-connection-and-node-access/5417/2 "2019-01-19T03:17:54Z")

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> [@NormandRobert](#):
>
> How long to wait before I get correct values?

Connections are managed in background threads. If you want to know when a client is connected then add an observer to the connector node.